I had this problem, with a 98 model, there is a known issue with them and the throttle body may need cleaning, this solved it for me however i think you can widen something in there to rectify
Adam, June 2008
Hi Karl, most likely cause the idle control valve sticking they get gummed up with petrol deposits, you will have to remove it and clean it with spray "carb cleaner" don't use anything else as it will only cause more sticking
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